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WEBrick is a Ruby library providing simple HTTPweb server services. WEBrick was primarily written by Masayoshi Takahashi and Yuuzou Gotou, with contributions from other developers via the open source model of software development. The server also provides code for simple server services other than HTTP.

It is used by the Ruby on Rails framework to test applications in a development environment. Despite its popularity WEBrick has gained some notoriety since the code is completely undocumented.